Phase stabilized solution combustion processed (Ce0.2La0.2Pr0.2Sm0.2Y0.2) O1.6-δ: An exploration of the dielectric properties

High entropy oxide (HEO) (Ce0.2La0.2Pr0.2Sm0.2Y0.2)O1.6-& delta; with a phase pure fluorite was synthesized using low-temperature solution combustion. A low-temperature formation of HEO was evidenced at 500 oC. The HEO formation at 500 oC was due to the exothermicity of the combustion redox reaction, where the internal temperature might have reached a much higher temperature for a limited amount of time. The presence of Sm2O3 and Y2O3 was visible upto 500 oC, while La2O3 was detected up to 900 oC and the HEO fully got stabilized at 1000 oC with a single-phase, fcc fluorite structure with an Fm-3 m space group. The HEO displays one of its parent oxide Ce-O structural properties as both belong to the fluorite family and had lattice parameters very close to each other. The presence of a secondary phase in the 2 and 3-cation systems and the display of a single phase in the 4 and 5-cation systems indicated the role of configurational entropy in phase stabilization. Raman of HEO also affirmed the formation of HEO at 500 & DEG;C, the complete elimination of secondary phases at 1000 & DEG;C, and a fully disordered occupancy of various metal cations with severe lattice distortion. A Flake morphology with a nanogranular cluster on the surface was displayed. Dielectric measurements at room temperature showed permittivity (& kappa;) & AP; 29 - 5.7 from 100 Hz to 1 MHz. & COPY; 2023 Elsevier B.V. All rights reserved.

Automated summary

High entropy oxide (HEO) (Ce0.2La0.2Pr0.2Sm0.2Y0.2)O1.6-δ with phase pure fluorite structure was synthesized using low-temperature solution combustion. The HEO formation at 500℃ was due to the exothermicity of the combustion redox reaction. The presence of different secondary phases and the role of configurational entropy in phase stabilization were observed.